Which equation is equivalent to x + 8 = 21?

Jack did 3/5 of all problems on his weekend homework before sunday. on sunday he solved 1/3 of what was left and the last 4 problems. how many problems were assigned for the weekend?

Write the equations in logarithmic form 9^4=6,561

Which graph of a hyperbola represents the equation 16x^2-y^2=16